Editing Audio crossover (section)

===Classification based on the number of filter sections===
Loudspeakers are often classified as "N-way", where N is the number of drivers in the system.  For instance, a loudspeaker with a woofer and a tweeter is a 2-way loudspeaker system. An N-way loudspeaker usually has an N-way crossover to divide the signal among the drivers.  A 2-way crossover consists of a [[low-pass]] and a [[high-pass]] filter.  A 3-way crossover is constructed as a combination of [[low-pass]], [[band-pass]] and [[high-pass]] filters (LPF, BPF and HPF respectively). The BPF section is in turn a combination of HPF and LPF sections. 4 (or more) way crossovers are not very common in speaker design, primarily due to the complexity involved, which is not generally justified by better acoustic performance.

An extra HPF section may be present in an "N-way" loudspeaker crossover to protect the lowest-frequency driver from frequencies lower than it can safely handle. Such a crossover would then have a [[bandpass filter]] for the lowest-frequency driver. Similarly, the highest-frequency driver may have a protective LPF section to prevent high-frequency damage, though this is far less common.

Recently, a number of manufacturers have begun using what is often called "N.5-way" crossover techniques for stereo loudspeaker crossovers. This usually indicates the addition of a second woofer that plays the same bass range as the main woofer but rolls off far before the main woofer does.

''Remark: Filter sections mentioned here is not to be confused with the individual 2-pole filter sections that a higher-order filter consists of.''